The aim of this randomized placebo-controlled study is to evaluate the effects of analgetics for neuropathic pain on mechanical hyperalgesia as a kind of evoked pain. Therefore the number of responders and non-responders on pregabalin will be evaluated in respect of mechanical hyperalgesia (stimulus-response-function (SRF) on static punctual stimuli evoking pain determined via pinprick). The hypothesis is that in the placebo group the amount of non-responders is increased.